Combining/reusing forms from different modules

Posted by joblogs83 on July 8, 2009 at 6:35am

What is the best way of combining forms in Drupal 6? For example, if I have a page comprising of:

+----------------------
| Field X
| Field Y
+----------------------
| 'user_register'
+----------------------
| Field Z
+----------------------

How would I go about inserting the core user_register module into that page, and how would I control validation/submission?

To date I've managed to use $form['user-register']['#value'] = drupal_get_form('user_register') but I'm having a lot of trouble with a) making some minor alterations to that original user_register form (using hook_form_alter) and b) controlling the validation and submission of the entire page.

I'm struggling to see any decent reading material on how to reuse existing forms - is this not a core principle of Drupal? It would be a ball ache to recode each form from scratch each time you want to use it as part of another form!

Thanks

Comments

I'd be interested as well.

Posted by traxer on July 23, 2009 at 7:17pm

I'd be interested as well. For the moment I am experimenting with '#after_build'. I let you know when I find out anything of use. Problems I have identified so far:

Both forms bring their own submit buttons.
For a given array key, an element might exist in both forms. This is a problem if '#tree' is false, because these elements then have the same name- and id-attribute in the HTML.
The value passed to '#element_validate' operates on the whole $form_state array. This means '#tree' cannot easily be changed to true, because the validation function will not find the submitted value.

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Got it

Posted by traxer on August 13, 2009 at 5:14pm

I found a solution.

The solution is not tested with ajax, neither is it tested with forms that do fancy stuff. FYI: cck does fancy stuff, but I've got a hack.

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Interesting

Posted by joblogs83 on August 25, 2009 at 2:34pm

I think your needs were a little different to mine based on your solution.

My resolution was something akin to:

* In hook_menu: define a path to load the 'user_register' form.
* In hook_alter: Check the path of the module, and if it's relevant, continue to alter it - otherwise leave it be.

I've now got three seperate registration forms - each serving a different purpose but each sharing a common form parent and overriding it as appropriate. You need to be careful with module weights and ensure your validate + submit handlers work correctly with the core form's functionality. Other than that you should be able to alter the form to your heart's content...